Typical surgical tourniquet systems of the prior art include a tourniquet cuff which encircles the limb of a surgical patient and a tourniquet instrument which is releasably connected to an inflatable bladder within the tourniquet cuff through a length of tubing, thereby establishing a gas-tight passageway between the cuff and the tourniquet instrument. The tourniquet instrument contains a pressurized gas source which is used to inflate and regulate the pressure in the tourniquet cuff above a minimum pressure required to stop arterial blood flow distal to the cuff, for a duration suitably long for the performance of a surgical procedure. Many types of surgical tourniquet systems have been described in the prior art, such as those described by McEwen in U.S. Pat. Nos. 4,469,099, 4,479,494, 5,439,477 and McEwen and Jameson in U.S. Pat. Nos. 5,556,415 and 5,855,589.
Standard cylindrical tourniquet cuffs are ideally suited for application to patients with cylindrical limbs. However, when applied to a patient with a tapered limb, a cylindrical cuff will not optimally match the limb taper, and will typically result in a snug fit proximally and a loose fit distally. Consequently, a cylindrical cuff may prove unable to achieve a bloodless field distal to the cuff at normal pressures or may require a substantially higher and more hazardous inflation pressure to achieve a bloodless field, and when inflated may have a tendency to roll or slide distally on the limb during a surgical procedure. In an effort to match the taper of a patient's limb at a desired cuff location, some tourniquet cuffs of the prior art are designed to have an arcuate shape, and are commonly called contour cuffs. When a contour cuff surrounds a limb having a matching taper, a uniformly snug fit can be achieved between the cuff and the limb from the proximal to distal cuff edges. Wide contour tourniquet cuffs of the prior art have been shown in the surgical literature to substantially reduce pressures required to create a bloodless surgical field distal to the inflated cuff (Younger et al., ‘Wide Contoured Thigh Cuffs and Automated Limb Occlusion Measurement Allow Lower Tourniquet Pressures’, Clin Orthop 428:286-293, 2004). Lower tourniquet pressures are associated in the surgical literature with lower risk of injuries to surgical patients.
Examples of contour cuffs of the prior art are described by Robinette-Lehman in U.S. Pat. No. 4,635,635, and in commercial products manufactured in accordance with its teachings (‘Banana Cuff’ sterile disposable tourniquet cuffs, Zimmer Arthroscopy Systems, Englewood Colo.). Cuffs described by Robinette-Lehman have an arcuate shape (defined by the distal radius), contain a single fastening system with fixed orientation, and include a rigid plastic stiffener. The cuff described in the '635 patent matches only a single limb taper for each particular cuff radius. For a limb with a differing taper, a cuff with a different arcuate shape matching that taper must be selected. When the cuff described by Robinette-Lehman '635 is applied to a limb with a differing taper, the overlapping proximal and distal edges of the cuff will not be superimposed upon one another, and will instead need to be skewed to obtain a sufficiently snug application and maximize the contact area between the cuff and the limb. The thick laminate construction and rigid stiffener included by Robinette-Lehman makes skewing the respective overlapping ends of the cuff difficult, and when skewed the orientation of the fixed fastening system may not be appropriate to safely and effectively allow the complete engagement of the velcro-type fastener to secure the cuff on the limb when inflated.
Other contour cuffs of the prior are described by McEwen in U.S. Pat. Nos. 5,312,431, 5,454,831, 5,578,055, 5,649,954, and 5,741,295. McEwegn '431 describes a cuff with an arcuate shape which overcomes the limitations noted above, by replacing the rigid stiffener with fluted welds in the bladder, and by including a complex pivoting means for securing the cuff around a limb having any one of a wide range of limb tapers at the cuff location. Although the cuff described by McEwen '431 provides increased safety and improved shape-matching over a wide range of limb tapers, it does so by including a number of expensive components and laminated materials, with subassemblies that are labor-intensive and time-consuming to manufacture. As a result, the contour cuff of McEwen '431 has a high cost of manufacture, preventing its cost-effective use as sterile disposable tourniquet cuff for single surgical procedures.
The prior-art contour cuff described in McEwen '431 employs multiple pivoting velcro-type hook fastening straps attached to D-shaped rings so that they may pivot when the cuff is wrapped around a tapered limb, and align with corresponding velcro-type loop material fastened to the surface of the cuff. These D-shaped ring assemblies are in turn attached near one end of the cuff. The ring assemblies allow the straps to pivot over a predetermined range when the cuff is wrapped around the limb to fully engage with the corresponding loop material on the outer surface of the cuff. Manufacturing the ring assemblies described in McEwen '431 requires relatively large amounts of different materials, and requires numerous labor-intensive steps including cutting, alignment, sewing and welding, all of which must be completed by skilled operators.
There is a need for a contour cuff for surgical tourniquet systems that overcomes the hazards, problems and limitations of performance associated with prior-art contour cuffs, and that can be manufactured at a cost that is substantially lower than prior-art contour cuffs.